redux-persist/autoRehydrate sub state for key "app" modified, skipping autoRehydrate

I have a substate called ‘app’ and my reducer does not listen on the REHYDRATE action type but it has an initial state. Despite this, I get the following logs: redux-persist/autoRehydrate sub state for key "app" modified, skipping autoRehydrate. What does it mean in detail and how can it be resolved?

Relevant code: https://github.com/rt2zz/redux-persist/blob/master/src/autoRehydrate.js#L60

[rt2zz]

@jeffreycrow this leads me to believe to that you are mutating state by default in your reducer.

e.g. if you use switch statements the default case should always return state unmodified, i.e.

//...
default: 
  return state

This will preserve object equality without requiring deep compares

[purplepeng]

Your Recommended Additions(set config.debug = true to get useful logging ) is very useful. I could not find my issue until open debug mode. Thanks, it’s great.